Monitoring rail infrastructure is important for both ensuring safety and determining the optimal timing for maintenance. Monitoring today is primarily performed through visual inspection that is both subjective and periodic. Railroad infrastructure has typically been monitored and inspected by a combination of visual inspections and specialty track inspection vehicles, known as track geometry cars. Additional tests such as ultrasonic rail inspection or track geometry assessments are performed using specialized rail vehicles, however, these vehicles are expensive to acquire and operate, and can disrupt traffic. As such, tracks are inspected infrequently. In addition, these tests are narrow in scope. For example, ultrasonic inspection only looks for internal material defeats in the “head” of the rail, the part of the rail in contact with the vehicle.
Proposals have been made to use vibration-based monitoring to assess the track profile as a lower-cost alternative to the type of optical sensors currently employed on track geometry cars. These proposals typically assume that the sensors are placed on the axle of the train so that they have a direct mechanical connection to the track. In addition, they assume the position of the train is known, typically achieved by requiring that the inspection car operate at a constant speed.
But perhaps the greatest shortcoming of the current systems is not the sensor configuration, but it is the method in which the data is analyzed. Most systems look for a particular type of track damage and trigger a detection when a certain data value (or feature value derived from this data) exceeds a certain threshold. Such a procedure is limited to detecting one or only a few types of damage, and can often be triggered falsely. For example, one prior art method detects squats in railway tracks, using such a threshold system. However locations that naturally cause large accelerations, like switch gear, need to be manually removed from the data so that they do not cause false alarms. A more robust system might detect changes relative to the historical behavior of the tracks rather than their current state. And such a method of analysis would allow the sensors to be placed anywhere on the train as will be discussed.
It would therefore be desirable to provide a system and method for performing vibration-based monitoring of track without the limitations of the current proposals.